This commit fixes links from Spring Framework's Dokka HTML to Javadoc
for Spring Framework and Servlet APIs by explicitly configuring the
`element-list` page as the `package-list` in the Dokka Gradle plugin.
Closes gh-32797
Due to an SSL/TLS issue with hamcrest.org, the Dokka task fails with the
following.
> Failed to download package-list from https://hamcrest.org/JavaHamcrest/javadoc/2.1/package-list,
> this might suggest that remote resource is not available, module is
> empty or dokka output got corrupted
See: https://github.com/hamcrest/JavaHamcrest/issues/280
As a workaround, this commit switches to javadoc.io to reference the
Hamcrest Javadoc APIs.
